Multi-layer, expandable sleeve for a printing press cylinder, particularly for flexographic printing

ABSTRACT

The invention relates to a multi-layer, expandable sleeve ( 100 ) for a printing press cylinder and to a method of manufacturing this expandable sleeve. The sleeve has an inner layer ( 110 ) with a hard surface inner jacket ( 112 ), which defines a longitudinal axis (A) and the cavity for mounting on the cylinder, and an outer layer ( 130 ) with a cylindrical outer jacket ( 132 ) for carrying an outer shell, a printing plate or a separate outer sleeve, in particular. An intermediate layer ( 120 ), manufactured in the form of a lightweight honeycomb having honeycomb cells oriented radially (B) to the longitudinal axis (A), is provided between the inner jacket ( 112 ) and the outer jacket ( 132 ). The intermediate layer ( 120 ) includes at least one honeycomb layer ( 122 - 1, 122 - 2, 122 - 3, 122 - 4, 122 - 5 ) of fibre composite honeycomb consisting of fibre material embedded in a resin matrix that has been applied coaxially around the longitudinal axis (A).

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of co-pending U.S. patent applicationSer. No. 13/825,672 filed Jun. 21, 2013, which is a Section 371 ofInternational Application No. PCT/EP2011/066542, filed Sep. 22, 2011,which was published in the English language on Mar. 29, 2012, underInternational Publication No. WO 2012/038514 A1, the disclosure of whichis incorporated herein by reference.

BACKGROUND OF THE INVENTION

1. Technical Field

The present invention generally relates to a multi-layer sleeve for useon a cylinder of a rotary press, wherein the sleeve is expandable, i.e.its inside diameter can be increased. The invention particularly relatesto a sleeve designed for flexographic printing, specifically forso-called variable-sleeve offset printing. The invention also relates toa corresponding manufacturing method.

2. Prior Art

Such sleeves are generally used to change the printing plate rapidly andinexpensively. They eliminate the need for changing the rotating, drivenprinting press cylinder itself. In the prior art, the term “sleeve”encompasses both adapter sleeves, which are mounted on the cylinder tocarry a further, thinner-walled sleeve, and also sleeves with an actualplate or plate holder, to which a typically flexible printing plate isapplied. Also known are sleeves where the plates are engraved directlyinto the outer surface, e.g. by laser, or applied in some other way.Furthermore sleeves are known whose surfaces serve as a cushioning,intermediate layer to accommodate comparatively rigid printing plateswith the actual printing plate. The present invention is fundamentallyapplicable both to the first two sleeve types and to the two lastmentioned types.

The sleeves are usually slid onto the carrier body, i.e. the printingpress cylinder, by generating an air cushion between the sleeve and thecylinder. To this end, the printing press cylinder typically has airoutlet openings on its surface that are only pressurised to mount anddismount the sleeve. The sleeves are designed to be expandable to thispurpose, i.e. with an expandable inside diameter. Multi-layer sleeveshave found widespread use in this context, in order to guaranteestability during operation, and particularly slip-free fixing on thecylinder by means of a non-rotating, frictional connection, despite theexpandable inside diameter.

A multi-layer sleeve designed specifically for flexographic printing isknown from European Patent Application EP 1 361 073, for example. Thissleeve encompasses, in a typical design, an inner layer with an innerjacket of comparatively high strength and/or surface hardness thatpermits frequent mounting and dismounting. The inner jacket isnevertheless elastically expandable to a minimum degree for mounting anddismounting. Expandability is additionally enabled, in whollyconventional manner, by a compressible layer being specially provided,radially outside the inner jacket. The compressible layer is customarilya relatively thin-walled layer of foamed polymer and permits reversibleexpansion of the inner jacket. The sleeve according to EP 1 361 073 hasan intermediate layer on the outside of the compressible layer. Thecustomary intermediate layer determines the wall thickness or theoverall diameter of the sleeve and is designed with a correspondingthickness. Particularly in the case of relatively large wallthicknesses, the intermediate layer should be made of the lightestpossible material, such as foamed polyurethane. According to theconventional design, as also proposed in EP 1 361 073, the intermediatelayer is, in contrast to the compressible layer, designed to be as rigidas possible, i.e. radially incompressible. The intermediate layer isthen followed by an outer layer. The latter, in turn, typically has anouter jacket that has the hardest possible surface and is usually notexpandable.

With the aim of increasing the service life and surface quality (TIR),U.S. Patent Application US 2002/0046668 proposes a multi-layer,expandable sleeve that comes entirely without a conventionalcompressible layer. The compressible layer is eliminated in that, as aresult of an appropriate design, the intermediate layer itself permits acertain degree of elastic expansion of the inner jacket, e.g. in therange of approx. 4 to approx. 12 hundredths of a millimetre. For anintermediate layer of this kind, US 2002/0046668 recommends a specialpolyurethane with a Shore D hardness between approx. 45 and 50.

Patent Specification EP 0 683 040 likewise discloses a sleeve without acompressible layer on the inner jacket. The sleeve according to EP 0 683040 also displays a multi-layer structure with an inner and outer jacketand an intermediate layer. Apart from the absence of a separatecompression layer, this sleeve has—with a view to saving weight and incontrast to US 2002/0046668—an intermediate layer of special,lightweight honeycomb design with radially oriented honeycomb webs (seeFIG. 3). This intermediate layer comprises layers of matting/resincomposite, between which at least one hexagonal honeycomb structure isformed, consisting of cured polymer resin. The hexagonal structure isproduced integrally from polymer resin. To this end, a strip of specialmatting that is specifically suitable for this purpose with impressedchannels and which does not itself absorb resin during impregnation, iswound around the matting layers in spiral fashion. The matting layersand the channels in the special strip are subsequently coated withresin, such that the matting layers are impregnated and the hexagonalchannel structure is filled with resin. After curing, this results in aspecial sandwich structure with honeycomb webs consisting exclusively ofpolymer resin. These webs form bridges between the matting/resin facelayers. According to EP 0 683 040, pillar-like resin bridges areadditionally provided within the non-impregnated hexagonal cells made ofmatting. They are produced by radial holes in the special matting,distributed around the circumference, which are likewise filled withresin. According to EP 0 683 040, the special design of the intermediatelayer itself, with hexagonal webs and supports made of resin between thematting/resin composite layers, is essential so that the inner jacketcan expand radially away from the longitudinal axis. According to EP 0683 040, several hundredths of a millimetre, i.e. at least 20 μm,expansion in the radial direction are said to be guaranteed.

The disadvantages of a sleeve according to EP 0 683 040 are at least therelatively complex process and the nevertheless comparatively highdensity i.e. volumetric weight of the special intermediate layer.

BRIEF SUMMARY OF THE INVENTION Object of the Invention

It is thus an object of the present invention to propose a sleeve and acorresponding manufacturing method that permit further weight reductioncompared to known sleeves.

Additionally or alternatively, the complexity of the process formanufacturing a sleeve with a lightweight intermediate layer is to bereduced, particularly when compared to EP 0 683 040.

These objects are achieved by a sleeve and a method according to theinvention.

General Description of the Invention

The invention relates to a multi-layer, expandable sleeve comprising aninner layer with an inner jacket having a wear-resistant, hard surface,preferably made of a composite fibre material that defines a cylindricalor conical cavity corresponding to the printing press cylinder. Thesleeve furthermore encompasses an intermediate layer generally designedas a lightweight honeycomb structure, in particular with honeycomb cellswhose central axes are oriented as radially as possible. In the knownmanner, the intermediate layer determines the overall diameter of thesleeve and can be designed with a correspondingly variable thickness. Anouter layer is provided on the outside of the intermediate layer. Saidouter layer has a cylindrical, compression-proof outer jacket,preferably made of a composite fibre material. The outer jacket serves,for example, to carry an outer shell, a printing plate or a separateouter sleeve (sleeve as an adapter sleeve).

According to the invention, the aforementioned object is achieved inthat the intermediate layer comprises at least one honeycomb layer witha shaped cured composite-fibre honeycomb made of fibre material embeddedin a resin matrix. The intermediate layer typically has a greaterthickness (radial dimension) than the inner layer or outer layer forexample, and preferably includes several such honeycomb layers.

Surprisingly, even with an intermediate layer of this kind withhoneycomb layers, it is possible for the inner jacket to be expandedradially away from the longitudinal axis, e.g. for mounting the sleeveon the cylinder. It may in particular permit expansion in the radialdirection of several hundredths of a millimetre, at least 10 μm,preferably at least 20 μm. Use of an additional compression layer as anauxiliary measure is possible, if so desired, but not necessary. Weightsavings are achieved by, inter alia, the low density of the honeycomblayers.

The use of composite-fibre honeycomb is in itself known in the field ofpress rollers. Up to now, however, the use of honeycomb was onlyproposed for applications where compressibility in the radial directionis to be minimised, not enabled, owing to the relatively high strengthin the web direction that is typical for honeycombs, e.g. on themulti-layer cutting roller from DE 100 18 418 with an intermediate layermade of lightweight CFRP or GFRP honeycomb material.

The invention also relates to a method for manufacturing a sleeveaccording to the invention.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

The foregoing summary, as well as the following detailed description ofthe invention, will be better understood when read in conjunction withthe appended drawings. For the purpose of illustrating the invention,there are shown in the drawings embodiments which are presentlypreferred. It should be understood, however, that the invention is notlimited to the precise arrangements and instrumentalities shown.

Further details and advantages of the invention can be taken from thefollowing, more detailed description of possible embodiments of theinvention on the basis of the enclosed drawings. The not-to-scaledrawings. show the following in schematic form:

FIG. 1 a cross-section of a first embodiment of an expandable sleevewith multi-layer structure, particularly suitable for large outsidediameters;

FIG. 2 a schematic side view in the radial direction according to arrowII in FIG. 1, illustrating the arrangement of two adjacent honeycomblayers in an intermediate layer of the sleeve according to FIG. 1;

FIG. 3 a cross-section of a second embodiment of an expandable sleevewith multi-layer structure, particularly suitable for smaller outsidediameters;

FIG. 4 a cross-section of a further embodiment of an expandable sleevewith multi-layer structure, as an alternative to FIG. 1;

FIG. 5 a cross-section of an alternative inner layer for use in a sleeveaccording to FIG. 4; and

FIG. 6 a cross-section of a further, alternative inner layer for use ina sleeve according to FIG. 4.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1 shows a first embodiment of an expandable sleeve, generallyreferred to as 100, in a cross-section at right angles to itslongitudinal axis A. Sleeve 100 has multiple layers and comprises,consecutively from the inside outwards, an inner layer 110, anintermediate layer 120 and an outer layer 130.

In the embodiment according to FIG. 1, inner layer 110 consists of agenerally rotationally symmetrical inner jacket 112, made of amulti-layer GFRP composite fibre material. Inner jacket 112 has a hardsurface, i.e. is sufficiently wear-resistant for a given number ofmounting and dismounting procedures. Inner jacket 112 is in itself notappreciably compressible, but its inside diameter can be elasticallyexpanded by several hundredths of a millimetre, particularly whenpressurised with compressed air in the pressure range typical forflexographic printing. As a rotational and hollow body, inner jacket 112defines longitudinal axis A of sleeve 100, as well as the inner cavityby means of which sleeve 100 is mounted on the cylinder of a rotarypress, particularly the compressed-air cylinder of a flexographic press,by expansion with compressed air. The terms “cylinder” and “cylindrical”are to be interpreted in the broadest sense here, i.e. inner jacket 112can have not only the known circular cylindrical geometry, but also aconically tapered geometry. Compared to the cylinder of the printingpress, inner jacket 112 often has a predefined, slight undersize, suchthat, when the compressed air is shut off, a slip-free frictionalconnection is ensured on the cylinder. Further details regarding thesuitable design of inner jacket 112 and inner layer 110 are prior art,e.g. according to the literature indicated in the introduction, and arethus not explained in more detail.

Like inner layer 110, outer layer 130 can also display an essentiallyconventional structure in itself. In the embodiment according to FIG. 1,outer layer 130 has a hard surface, compression-proof outer jacket 132made of composite fibre material, preferably multiple layers of GFRP. Incontrast to inner jacket 112, outer jacket 132 should preferably not beappreciably deformable when exposed to normal stresses from the insideor the outside. This is particularly achieved by a suitable combinationof resin and fibre material in outer jacket 132. For example, comparedto inner jacket 112, outer jacket 132 can display more layers than innerjacket 112 and/or a different fibre material, such as a differentfabric, or a less expansible combination of different fibre materialtypes, etc. Outer layer 130 according to FIG. 1 furthermore has anexternal outer shell 134 made of a hard, chemically resistant material,preferably polyurethane or a material with the same property profile.Outer shell 134 displays a technically circular-cylindrical outersurface about longitudinal axis A and is correspondingly machined, e.g.cylindrically turned, where appropriate. Outer shell 134 is attached toouter jacket 132. To this end, a thin, outer honeycomb layer (not shown)can optionally be attached to outer jacket 132 to improve connection,similar to the innermost honeycomb layer described further below, towhich outer shell 134 made of polyurethane is applied. Outer shell 134likewise has a hard surface and is compression-proof. Alternatively tothis, an elastic shell, e.g. made of rubber-like material, a separateouter sleeve, i.e. for use of sleeve 100 as an adapter sleeve, ordirectly the printing plate itself, for example, can be applied to outerjacket 132. However, the embodiment according to FIG. 1, with outershell 134 made of polyurethane, is preferred for flexographic printing.In the known manner, outer shell 134 thus forms the plate or plateholder for interchangeable attachment of a flexible plate. Suitableretaining means (not shown in detail) for flexographic printing plates,e.g. a milled retaining slit, can be provided in or on outer shell 134.Further details regarding the suitable design of an outer layer 130 areknown from the prior art.

FIG. 1 furthermore schematically shows the structure of intermediatelayer 120 according to one aspect of the invention. Intermediate layer120 is cylindrical and made of lightweight honeycomb material,particularly in multi-layer form with several layers of honeycombmaterial. Intermediate layer 120 is attached to inner layer 110, oninner jacket 112 according to FIG. 1, for example, preferably by meansof a suitable adhesive layer 114. In contrast, outer layer 130 can beattached to intermediate layer 120 made of honeycomb material eitherdirectly, e.g. by winding impregnated fibre material, or additionally bya separate adhesive layer.

As can best be seen from FIG. 2, honeycomb cells 123 of the individuallayers of intermediate layer 120 are arranged in such a way that theircentral axes B (transverse to the plane of FIG. 2) are orientedessentially radially to longitudinal axis A. Thus, central axes Bradiate from longitudinal axis A in a star-shaped arrangement,preferably in the plane of FIG. 1. In the unshaped flat state, a centralaxis B corresponds to the axis of symmetry of honeycomb cell 123 in thedirection of the honeycomb thickness parallel to the cell walls. Owingto the curvature-induced expansion of honeycomb cells 123 (see below),the cells walls, i.e. honeycomb webs 126, are not exactly parallel tocentral axis B, but are likewise essentially radial. FIG. 2 shows anidealised, schematic view without corresponding curvature, Of course,curvature-induced deformations and a lesser degree of symmetry in thecross-section of honeycomb cells 123 according to FIG. 2 cannot beavoided in practice.

As can be seen from FIG. 1 and FIG. 2, intermediate layer 120 is made ofseveral, adjacent honeycomb layers 122-1, 122-2, 122-3, 122-4, 122-5.Every single honeycomb layer 122-1, 122-2, 122-3, 122-4, 122-5 ofintermediate layer 120 is manufactured according to the invention, withshaped cured fibre composite honeycomb made of fibre material embeddedin a resin matrix. In this context, the term “shaped cured” means thatthe individual honeycombs of each honeycomb layer 122-1, 122-2, 122-3,122-4, 122-5 already form an actual fibre composite, i.e. are curedbefore being placed on top of each other during production ofintermediate layer 120. Moreover, the term “honeycomb” is not used hereto denote a single (honeycomb) cell, but the coherent structure ofcells. The fibre composite honeycombs of each honeycomb layer 122-1,122-2, 122-3, 122-4, 122-5 can, in principle, be manufactured from anysuitable combination of glass fibres, carbon fibres, aramid fibres, ormixtures thereof, with epoxy resins, vinyl ester resins, polyesterresins, phenolic resins or other types of resin, including hybridresins, where appropriate. However, honeycomb made of aramid fibrepaper, particularly of Nomex® paper, in conjunction with phenolic resin(e.g. of the Euro-Composites® ECA/ECA-R type) is particularly preferredfor weight and cost optimisation. As can furthermore be seen from FIG.1, honeycomb layers 122-1, 122-2, 122-3, 122-4, 122-5 are directlyattached to each other, on top of each other and between each other, bymeans of intermediate adhesive layers 124, coaxially to axis A. Suitablefor adhesive layers 124 is, for example, adhesive film based on epoxyresin or of thermoplastic adhesive. Adhesive layers 124 preferably havea weight per unit area of <500 g/m² and preferably consist of pure,cured adhesive, e.g. resin without fibre reinforcement, in order toguarantee a minimum of elastic deformation. In other words, in contrastto the prior art, no sandwich-typical face layers of fibre composite areprovided in the circumferential direction within intermediate layer 120,but pure, non-reinforced adhesive layers 124, e.g. of epoxy resin orthermoplastic material. This has proven to be advantageous for expansionof inner layer 110 and is presumably decisive in this respect.

Despite the characterising application of fibre composite honeycomb toachieve high resistance to compression in the direction of central axesB of honeycomb cells 123, the structure of intermediate layer 120proposed here is surprisingly capable of achieving sufficient expansionof inner layer 120 and of inner jacket 122 of several hundredths of amillimetre in the radial direction, particularly of more than 30 μm.This property is presumably attributable to production-related effects,such as the expansion of honeycomb cells 123 in the radial direction,and also to their direct connection to each other by means ofnon-reinforced adhesive layers 124.

Ideal values were obtained in an embodiment schematically illustrated inFIG. 2. In this instance, two radially adjacent pairs of honeycomblayers, 122-1/122-2, 122-2/122-3, 122-3/122-4 and 122-4/122-5 (thelatter pair is shown in FIG. 2), are in each case arranged in such a waythat central axes B of honeycomb cells 123 of outer honeycomb layer122-5 are, as far as possible, offset relative to the central axes ofthe honeycomb cells of adjacent inner honeycomb layer 122-4, at leastover a material portion of the circumference, viewed around longitudinalaxis A. In other words, alignment of central axes B between twoimmediately adjacent honeycomb layers 122-1/122-2, 122-2/122-3,122-3/122-4 or 122-4/122-5 is avoided to the extent technically possiblein the framework of production. Alignment of this kind can betechnically avoided relatively easily, at least over a portion of thecircumference exceeding 75% of the circumference on the statisticalaverage. In contrast, alignment between non-adjacent honeycomb layers,e.g. innermost honeycomb layer 122-1, middle honeycomb layer 122-3and/or outer honeycomb layer 122-5, is perfectly permissible,irrelevant, and sometimes even advantageous. Applying appropriateprecision during production, manufacturing is preferably performed insuch a way that, as illustrated in FIG. 2, the honeycombs in pairs ofradially adjacent honeycomb layers, e.g. 122-4/122-5, are offset in sucha way that cell webs 126, i.e. the radially oriented cell walls, ofhoneycomb cells 123 of inner honeycomb layer 122-4 (shown in FIG. 2)support cell webs 126 of outer honeycomb layer 122-5 centrally withinthe bounds of the technically feasible. Put another way, in a radialside view according to FIG. 2, adjacent cell webs 126 are supposed tointersect as centrally as possible. As a result, cell webs 126 typicallybear loads at four points each, as exemplified in C in FIG. 2 (similarto a four-point bearing). For manufacturing reasons, it is, of course,impossible to completely rule out slight, unintentional alignment overlimited angular ranges (sectors about longitudinal axis A). Equally,central load bearing of cell webs 126 on each other cannot be exactlyguaranteed. On average, the arrangement of two adjacent honeycomblayers, e.g. 122-4/122-5, can and should, however, for the greater partdisplay the above-mentioned offset or central load bearing, rather thanalignment of central axes B and cell webs 126. This preferredarrangement additionally improves the already surprising radialcompressibility of intermediate layer 120 towards the outside, whichguarantees the expandability of inner layer 110. The pairwisenon-aligned arrangement obviously requires that the pairs of adjacenthoneycomb layers, e.g. 122-2/122-3, 122-3/122-4 and 122-4/122-5, each bemanufactured from fibre composite honeycomb of identical cell size. As aresult and despite expansion towards the outside, the cell cross-sectionof adjacent honeycomb cells 123 coincides almost exactly at theirinterface, i.e. at the level of adhesive layer 124 between them.

It should furthermore be noted that intermediate layer 120 preferablydisplays an innermost honeycomb layer 122-1 made of shaped cured fibrecomposite honeycomb with hexagonal honeycomb cells (not shown in moredetail). Thus, unlike honeycomb cells 123 of the further outer honeycomblayers 122-2, 122-3, 122-4, 122-5, shown in FIG. 2, innermost honeycomblayer 122-1 has no overexpanded honeycomb cells. In contrast, honeycombcells 123 of the further outer honeycomb layers 122-2, 122-3, 122-4,122-5 are overexpanded, preferably in the direction of longitudinal axisA, i.e. at least not regularly hexagonal, as schematically illustratedin FIG. 2. Not shown in more detail in FIG. 2 is the preferredembodiment with honeycomb cells 123 that are completely overexpanded (inthe W or L direction), i.e. overexpanded into a quasi-rectangularcross-section (“overexpanded rectangular core”, e.g. of theEuro-Composites® ECA-R type). Corresponding overexpansion of the fibrecomposite honeycomb before its curing greatly facilitates its subsequentbending into the cylindrical jacket shape about axis A, and reduces theassociated warping. Furthermore, the embodiment according to FIG. 1displays the preferred characteristic that innermost honeycomb layer122-1, made of hexagonal honeycomb, displays a substantially smallerthickness (dimension in the radial direction), compared to the furtherouter honeycomb layers 122-2, 122-3, 122-4, 122-5. A thickness ofinnermost honeycomb layer 122-1, made of hexagonal honeycomb, of lessthan 10%, preferably less than 7.5%, of the total thickness ofintermediate layer 120 emerged in experiments. In order to guaranteepracticable bending of innermost honeycomb layer 122-1, made ofhexagonal honeycomb, and given customary inside diameters of sleeve 100,said innermost honeycomb layer 122-1 preferably has a thickness of lessthan 7.5 mm, preferably 5 mm, in absolute terms. Hexagonal honeycomb ina thin innermost honeycomb layer 122-1 is particularly preferredtogether with an auxiliary layer of foamed polymer, as described furtherbelow (FIGS. 5, 6). An arrangement comprising a thin, relatively morestable innermost hexagonal honeycomb layer 122-1 and an adjacent,overexpanded honeycomb layer 122-2 according to FIG. 1 is apparentlyalso beneficial to expansion, this possibly being attributable tofavourable bending properties at the points of intersection of thehexagonal and overexpanded honeycomb webs 126.

Not to be seen in more detail from FIG. 1 is the preferred embodimentaccording to which intermediate layer 120 comprises honeycomb layers122-1, 122-2, 122-3, 122-4, 122-5 of at least three differentthicknesses, increasing towards the outside. For instance, innerhoneycomb layer 122-1 can display a thickness of approx. 1.5-3.5 mm, thethickness of outer honeycomb layers 122-2, 122-3, 122-4, 122-5 being inthe range 7.5-12.5 mm, 12.5-17.5 mm and 17.5-25 mm in each case, inwhich context the two middle honeycomb layers 122-3, 122-4, for example,can display the same thickness of 12.5-17.5 mm. Similarly, instead of alayer 122-5 in the range from 17.5 mm to 25 mm, it is also possible toprovide a plurality of identical layers, e.g. four to seven such layers,depending on the required outside diameter. Fine-tuning of the overallthickness of intermediate layer 120 can be achieved by again applyingappropriately selected honeycomb layers of lesser thickness on theoutside of the one or more thickest layers (see example below).

FIG. 3 shows a generic sleeve 200 according to a second embodiment. Likethe embodiment in FIG. 1, it has no separate compression layer, ascustomarily used. In this embodiment, too, the sleeve has a multi-layerstructure with an inner layer 210, comprising a GFRP inner jacket 212,an intermediate layer 220 and a relatively rigid outer layer 230 with anouter jacket 232 and a polyurethane outer shell 234. Sleeve 200essentially differs in that a smaller number of honeycomb layers ispresent, e.g. merely two honeycomb layers 222-1, 222-2, as illustrated,where innermost honeycomb layer 222-1 is preferably relatively thin,particularly having a thickness <<10 mm, and manufactured from hexagonalhoneycomb, and outer honeycomb layer 222-2 is relatively thick, e.g.having a thickness >15 mm, and manufactured from completely overexpandedhoneycomb (e.g. of the Euro-Composites® ECA-R type). Apart from havingdifferent diameters, the structure of inner layer 210 and outer layer230 can correspond to the above description. What was said abovesimilarly applies to the structure of individual honeycomb layers 222-1,222-2. In the embodiment according to FIG. 3, too, intermediate layer220, made of shaped cured fibre composite honeycomb, in itself thuscontributes essentially to inner jacket 212 being able to expandradially away from longitudinal axis A for mounting sleeve 200 on aprinting press cylinder. An intermediate layer 220 with a relativelythin overall thickness likewise permits expansion of at least 20 μm (2hundredths of a millimetre) in the radial direction.

FIG. 4 shows a further embodiment of a sleeve 300 as an alternative toFIG. 1. Sleeve 300 essentially differs as regards the structure of itsinner layer 310. Although illustrated differently, intermediate layer320 can be essentially structured as described above in relation to FIG.1 or, however, without a thin innermost layer (see FIG. 1, Ref. 122-1)and/or with a different arrangement of honeycomb layers 322-1, 322-2,322-3. Outer layer 330 is designed as described above for use inflexographic printing.

In contrast, inner layer 310 according to FIG. 4 comprises, in additionto the hard surface inner jacket 312 described above and from the insideoutwards, a compressible auxiliary layer 316 and, for manufacturingreasons, an intermediate jacket 318. Compared to outer jacket 332,intermediate jacket 318 is likewise relatively elastic, e.g. made offibre composite, preferably of just a few layers of GFRP, in order topermit the required expansion. Intermediate layer 320 according to theinvention is produced and attached on intermediate jacket 318. Auxiliarylayer 316 according to FIG. 3 consists of compressible material,particularly a foamed polymer with a density in the range of 25-40kg/m³. An elastomer or a foam type with the most durable possiblepreservation of >90% resilience is preferred.

An embodiment with auxiliary layer 316 according to FIG. 4 is preferred,particularly if, in addition to the essential contribution made byintermediate layer 320, an additional contribution to the expansibilityof inner jacket 312 is required or, for example, the non-slip frictionalconnection on the cylinder is to be specifically influenced by means ofsuitable selection of the material of auxiliary layer 316. Compared tointermediate layer 320, auxiliary layer 316 makes a smaller contribution(<50%), also in the embodiment of sleeve 300 according to FIG. 4, toradial expansion in relation to longitudinal axis A in absolute terms(not in relation to length). Thus, in the embodiment according to FIG.4, too, >50% of the expansion in the radial direction in absolute termsis absorbed by intermediate layer 320, e.g. on the basis of a structureaccording to FIG. 1. Accordingly, the contribution of intermediatejacket 318 to expansibility is preferably <50%.

FIGS. 5 and 6 show preferred alternatives for an inner layer 410, 510with a compressible auxiliary layer, which can particularly also beincorporated separately into structures according to FIG. 1, FIG. 3 orFIG. 4 as an inner layer. In this context, said structures then displayan inner jacket 112, 212 or an intermediate jacket 314 of lesserthickness and an oversize corresponding to the diameter of the innerlayer according to FIG. 5 or FIG. 6, plus an assembly gap of approx.0.1-0.5 mm for bonding.

Inner layer 410 according to FIG. 5 comprises, from the inside outwards,a hard surface inner jacket 412, a compressible auxiliary layer 416,particularly made of an elastomer or foamed polymer, as above, and athin honeycomb layer 422. Thin honeycomb layer 422 is attached adjacentto compressible auxiliary layer 416, i.e. the foamed polymer, by meansof a suitable, non-reinforced, elastically deformable adhesive layer414. Thin honeycomb layer 422 is particularly manufactured from shapedcured fibre composite honeycomb, preferably with hexagonal honeycombcells having a thickness ≦7.5 nun. For manufacturing purposes, innerlayer 410 additionally comprises an outer intermediate jacket 418,preferably made of composite fibre material, which can be designed to beof comparatively small thickness, such that, when bonded together with afurther intermediate jacket, e.g. 318 in FIG. 4, it does not impair theessential contribution to expansion in the radial direction of theintermediate layer, e.g. 320 in FIG. 4. A polyurethane-based or epoxyresin-based paste adhesive is preferred as adhesive layer 414, appliedadjacent to auxiliary layer 416 made of an elastomer or a foamedpolymer.

The structure of inner layer 510 according to FIG. 6 is identical, apartfrom the sequence from the inside outwards, where thin honeycomb layer522 is provided on the inside, and compressible auxiliary layer 516 onthe outside in FIG. 6.

Compared to inner layer 310 according to FIG. 4, for example, use of aninner layer 410; 510 according to FIG. 5 or FIG. 6 permits an increasein the possible compression or a lesser thickness of compressibleauxiliary layer 416; 516, since the latter can, particularly when usingfoam material, at least slightly escape into the open honeycomb cells ofthin honeycomb layer 422; 522.

Possible manufacturing methods for sleeves 100; 200; 300, withintermediate layer 120; 220; 320 and/or inner layer 310; 410; 510according to the invention, are described below on the basis ofpreferred exemplary embodiments:

As a general overview, the method for manufacturing a multi-layer,expandable sleeve typically comprises Steps A) to C), as follows:

A) production of an inner layer 110; 210; 310 with a hard surface innerjacket 112; 212; 312, preferably from composite fibre material, on amandrel defining a longitudinal axis, preferably by means of

-   -   application, preferably by winding, of dry or resin-impregnated        fibre material on the mandrel in one or more layers,    -   impregnation of the fibre material with resin by vacuum        infusion, or by the wet-winding technique directly during        winding,    -   curing of the impregnated fibre material to obtain a hard        surface inner jacket;

B) production of an intermediate layer 120; 220; 320 in the form of alightweight honeycomb, with honeycomb cells whose central axes areoriented radially to the longitudinal axis by

-   -   application of an adhesive layer 124; 224; 324, particularly on        the produced inner layer 110; 210; 310;    -   application of at least one honeycomb layer 122-i; 222-i; 322-i,        made of previously cured fibre composite honeycomb consisting of        fibre material embedded in a resin matrix, coaxially to        longitudinal axis A, where fibre composite honeycomb layer        122-i; 222-i; 322-i is shaped during application or beforehand        for bending it into curvature about longitudinal axis A. In this        context, the cell sizes of the honeycombs are preferably in the        range from 3.2 to 6.4 mm. The densities of the honeycomb layers        are preferably in the range from 38 to 52 kg/m³. Phenolic        resin-impregnated aramid fibre honeycomb is preferably used as        the honeycomb material (e.g. ECA honeycomb from Euro-Composites®        S.A.). Bonding of the honeycomb layers by the adhesive layers is        performed in an oven cycle at 50 to 160° C., depending on the        adhesive type used.

C) production of an outer layer 130; 230; 330 with a hard surface,cylindrical outer jacket 132; 232; 332, preferably made of compositefibre material, on intermediate layer 120; 220; 320, preferably by

-   -   application, e.g. by winding, of fibre material pre-impregnated        with resin, preferably epoxy resin or vinyl ester resin, in one        or more layers, indirectly or directly on the intermediate        layer, particularly on the outer honeycomb layer, and    -   curing of the pre-impregnated fibre material to obtain a hard        surface outer jacket,    -   application of an outer, hard layer made of chemically resistant        material, preferably polyurethane or a material with a similar        property profile, by suitable application methods (e.g. casting,        spraying or spin coating).

As an alternative to manufacturing intermediate layer 320 directly onthe complete inner layer 310, it is also possible to manufactureintermediate layer 320 on a first intermediate jacket 318, into which aseparate inner layer 410; 510 according to FIG. 4 or FIG. 5 issubsequently bonded. In this case, inner layer 410; 510 is thus producedseparately and independently in terms of time. This procedureparticularly permits the production of modular intermediate layers 120;220; 320, which can be provided with an inner jacket of the requireddiameter. Similarly, outer layer 130; 230; 330 can comprise, in additionto compression-proof outer jacket 132; 232; 332 and possibly outer shell134; 234; 334, one or more inner spacer layers, subsequently applied toa modular intermediate layer 120; 220; 320, particularly also made ofshaped cured fibre composite honeycomb.

Finally, it should once again be noted that, according to the invention,the use of at least one honeycomb layer made of shaped cured fibrecomposite honeycomb, e.g. according to FIG. 1, FIGS. 3-4, or also FIGS.5-6, achieves simplified manufacturing and low weight. Furthermore,while achieving low weight, an intermediate layer is made possible thatpermits significant expansion in the radial direction, particularlyexpansion by at least 20 μm.

In fact, contrary to expectations, a structure of the intermediate layerusing shaped cured composite-fibre honeycomb, i.e. honeycomb made offibre material embedded in a resin matrix, is also capable of achievingat least a major portion of the necessary compressibility through theintermediate layer itself (much like the more elaborate and heavierstructure according to EP 0 683 040).

It will be appreciated by those skilled in the art that changes could bemade to the embodiments described above without departing from the broadinventive concept thereof. It is understood, therefore, that thisinvention is not limited to the particular embodiments disclosed, but itis intended to cover modifications within the spirit and scope of thepresent invention as defined by the appended claims.

I/We claim:
 1. A multi-layer, expandable sleeve for a printing presscylinder, the sleeve comprising, from the inside outwards, at least: aninner layer comprising an expandable inner jacket, a compressibleauxiliary layer, and an intermediate jacket, the inner jacket defining alongitudinal axis and a cavity for mounting the sleeve on the cylinder;an intermediate layer comprising a lightweight honeycomb structure withhoneycomb cells, and an outer jacket for carrying an outer shell, aprinting plate or a separate outer sleeve, wherein the intermediatelayer comprises at least one honeycomb layer made of fibre compositehoneycomb that consists of fibre material embedded in a resin matrix,and wherein the fibre composite honeycomb has been shaped so thatcentral axes of the honeycomb cells are oriented as radially as possiblewith respect to the longitudinal axis.
 2. The multi-layer, expandablesleeve according to claim 1, wherein the at least one honeycomb layer ismade of previously cured fibre composite honeycomb.
 3. The multi-layer,expandable sleeve according to claim 1, wherein at least one of the hardsurface inner jacket, the intermediate jacket and the outer jacked ismade of composite fibre material.
 4. The multi-layer, expandable sleeveaccording to claim 1, wherein the outer jacket is made of compositefibre material and compression-proof.
 5. The multi-layer, expandablesleeve according to claim 1, wherein the inner jacket is made ofcomposite fibre material and has a hard surface.
 6. The multi-layer,expandable sleeve according to claim 1, wherein the intermediate layercomprises at least two honeycomb layers, which are each manufacturedfrom shaped cured fibre composite honeycomb and attached coaxially tothe longitudinal axis, one on top of the other.
 7. The multi-layer,expandable sleeve according to claim 6, wherein neighbouring honeycomblayers are attached by means of non-reinforced adhesive layers.
 8. Themulti-layer, expandable sleeve according to claim 6, wherein tworadially adjacent honeycomb layers are arranged in such a way that thecentral axes of the honeycomb cells of the outer honeycomb layer areoffset relative to the central axes of the honeycomb cells of theadjacent inner honeycomb layer over a material portion of thecircumference.
 9. The multi-layer, expandable sleeve according to claim8, wherein two radially adjacent honeycomb layers are manufactured fromfibre composite honeycomb of the same cell size, and the central axesare offset in such a way that the cell webs of the inner honeycomb layerbear the cell webs of the outer honeycomb layer essentially centrally.10. The multi-layer, expandable sleeve according to claim 6, wherein theintermediate layer comprises honeycomb layers of at least threedifferent thicknesses, increasing towards the outside.
 11. Themulti-layer, expandable sleeve according to claim 1, wherein allhoneycomb layers of the intermediate layer are manufactured from shapedcured honeycomb made of aramid fibre paper and phenolic resin.
 12. Themulti-layer, expandable sleeve according to claim 1, wherein an outerlayer made of polyurethane is attached on the outer jacket.
 13. Themulti-layer, expandable sleeve according to claim 1, wherein thecompressible auxiliary layer is made of an elastomer or of a foamedpolymer.
 14. A multi-layer sleeve for a printing press cylinder, thesleeve comprising at least: an inner jacket that is made of compositefibre material and defines a longitudinal axis and a cavity for mountingthe sleeve; an intermediate layer comprising a lightweight honeycombstructure, including at least two honeycomb layers having honeycombcells, each layer being made of fibre composite honeycomb that consistsof fibre material embedded in a resin matrix, the fibre compositehoneycomb having been shaped so that central axes of the honeycomb cellsare oriented as radially as possible with respect to the longitudinalaxis, the honeycomb layers being attached coaxially to the longitudinalaxis, one on top of the other; and an outer jacket that is made ofcomposite fibre material for carrying an outer shell, a printing plateor a separate outer sleeve.
 15. The multi-layer sleeve according toclaim 14, further comprising an inner layer including the inner jacket,a compressible auxiliary layer and an intermediate jacket, wherein theinner jacket is expandable.
 16. The multi-layer sleeve according toclaim 14, wherein the outer jacket is manufactured from multi-layer,glass fibre-reinforced plastic, and wherein an outer layer is attachedon the outer jacket, the outer layer being made of polyurethane.
 17. Amethod of manufacturing a multi-layer sleeve for a printing presscylinder, the method comprising: providing an inner layer structureincluding a hard surface inner jacket made of composite fibre material,on a mandrel defining a longitudinal axis; providing an intermediatelayer made of a lightweight honeycomb structure, comprising: applying ofan adhesive layer on the inner layer structure; applying at least onehoneycomb layer, made of fibre composite honeycomb consisting of fibrematerial embedded in a resin matrix, coaxially to the longitudinal axis,shaping the fibre composite honeycomb, when applying it coaxially orbeforehand, for bending the honeycomb about the longitudinal axis sothat the central axes of the honeycomb cells are oriented as radially aspossible with respect to the longitudinal axis, and providing an outerlayer with a compression-proof outer jacket made of composite fibrematerial on the intermediate layer.
 18. The method according to claim17, wherein manufacturing of the inner layer structure comprisesapplying at least one compressible auxiliary layer of an elastomer or ofa foamed polymer on the inner jacket.
 19. The method according to claim18, wherein providing the inner layer structure comprises: applyingresin-impregnated glass fibre material on the mandrel in one or morelayers or applying dry glass fibre material and impregnating the dryglass fibre material with resin; curing the impregnated fibre materialto obtain an inner jacket; applying at least one compressible auxiliarylayer on the inner jacket; applying resin-impregnated fibre material onthe mandrel in one or more layers by a wet winding technique; and curingthe impregnated fibre material the inner layer structure.
 20. The methodaccording to claim 18, wherein providing an outer layer comprises:applying fibre material pre-impregnated with resin, in one or morelayers, indirectly or directly on the intermediate layer; and curing thepre-impregnated fibre material to obtain a compression-proof outerjacket.
 21. The method according to one claim 17, wherein manufacturingof the intermediate layer comprises: applying at least two honeycomblayers with intermediate non-reinforced adhesive layers, wherein thehoneycomb layers are made of previously cured fibre composite honeycombconsisting of fibre material embedded in a resin matrix, and are shapedduring application or beforehand for bending about the longitudinalaxis; and attaching each honeycomb layer directly to an adjacent, innerhoneycomb layer, or indirectly or directly on the inner layer structure,by curing the respective non-reinforced adhesive layers between them.22. The method according to claim 21, wherein at least two honeycomblayers are consecutively applied in such a way that, in two radiallyadjacent honeycomb layers, the central axes of the honeycomb cells ofthe outer honeycomb layer are offset relative to the central axes of thehoneycomb cells of the adjacent inner honeycomb layer over a materialportion of the circumference, and the central axes are offset in such away that the cell webs of the inner honeycomb layer bear the cell websof the outer honeycomb layer essentially centrally.
 23. The methodaccording to claim 21, wherein at least two honeycomb layers areconsecutively applied in such a way that two radially adjacent honeycomblayers are manufactured from fibre composite honeycomb of the same cellsize.